A researcher has observed that children who eat more sugar tend to show a higher level of activity than children who eat less sugar. However, the researcher suspects that the apparent relationship may be explained by the fact that some children have a higher rate of metabolism, which causes them to eat more and to be more active compared to children with a lower rate of metabolism who eat less and are less active. This is an example of the .

The correct answer is the third variable problem

A system of equations can be formed by several unknowns, but it will only be solved if the number of unknown terms is equal to the number of equations in the system. The systems with three variables can be solved through the processes already known and studied, substitution or addition.

cannabis

explanation:

(assuming this is the us) google it. law states you can't have weed.

explanation:

with the profits from the european sales, merchants purchased europe's manufactured  goods, including tools and weapons. then the merchants shipped those manufactured  goods, along with the  american  sugar and rum, to west africa where they were bartered for  slaves.